The brush riggings for motors and generators and the like vary in design, but in general consist of boxes to house the brushes, a spring means to apply pressure to the brushes to urge them against a commutator, connecting electrical leads to provide a current path to the brushes and a mounting surface to secure these elements as well as to provide some means to secure the entire assembly to the motor in such a manner as to place the brushes in a proper working relationship with the commutator.
One of the most popular designs, especially for small fractional horsepower motors, is to utilize a molded brush card member of a one-piece construction formed from a high temperature resistant plastic which is electrically nonconductive. The member has the brush boxes formed thereon as well as various openings for securing it to the motor housing and for receiving an extending armature shaft and the commutator secured to the shaft.
The prior riggings present problems when they are contemplated for use in an automated assembly process. In particular, while assembling the armature in a motor, complicated movements would have to be performed by the automation equipment to hold the brushes back in the brush box against the pressure being applied to the brushes by the spring means until such time as the commutator is positioned to receive the brushes.
Although this is particularly a problem for automated assembly of motors, it also applies to those units being assembled by hand in that special tools and fixtures have previously been used to hold the brushes while the armature is being assembled. The brush holder as described herein would avoid the need for this equipment.
The herein-described brush holder is a molded brush card member having a displaceable section which acts to secure the brushes within the brush box until such time as the armature is assembled thereto. The displaceable section is designed such that upon assembly, the armature to the motor acts to displace the displaceable section thereby releasing the brushes and allowing the brush springs to urge the brushes against the commutator.
Several embodiments are disclosed herein with the displaceable section being designed for varying purposes in each. In one embodiment the displaceable section is a washer-like member which serves as a thrust washer and/or an oil slinger on the armature shaft after it is displaced to release the brushes.
Another embodiment discloses breakaway sections which merely fall to the bottom of the motor housing after they are displaced. A third embodiment discloses fingers which are bent relative to the brush card holder as the armature is assembled.